Medical Device Daily National Editor

Animal cells (of the homo sapiens type, too) and bacteria organisms dance on the surfaces of almost everything. And on many surfaces these are not the dances of life. Free-floating microorganisms tend to light here and there and, if not removed, begin to adhere to one another, colonizing, spreading.

The result is the formation of a matrix covering the surfaces they contact, corroding the hulls of ships, covering rocks with green slime, polluting drinking water, forming plaque on teeth, and sticking to medical devices, many implanted in humans — this later activity resulting in infection and inflammation, at times rejection of the devices they cover, all serious, frequently life-threatening and life-taking, circumstances.

Now, two researchers at Syracuse University (SU; Syracuse, New York) say they have discovered new ways to prevent these conglomerations of microscopic life forms – called biofilms – and the damage they produce, resulting in billions of dollars of damage every year.

In their interdisciplinary collaboration, Yan-Yeung Luk, SU assistant professor of chemistry, and Dacheng Ren, assistant professor of biomedical engineering in SU's L.C. Smith College of Engineering and Computer Science, the researchers found that if you can prevent protein from sticking to a surface, you also can prevent both bacteria and mammalian cells from doing so. In the process they have developed a surface technology that they believe scientists also will be able to use to study biofilms in ways not previously possible.

Over the past three years, Luk and Ren developed a common thread in their individual research efforts — the desire to chemically modify surfaces to prevent biofouling, and they created a surface that appears to repel both bacteria and mammalian cells.

Luk described the starting point of the surface developed as a thin film of gold, coated on a glass slide. They then added organic molecules of sugar alcohols that disrupt protein structures at the intersection between the surface and the damaging living material, using processes based on theories that the two researchers acknowledge were developed 100 years ago.

The surface the researchers created was able, in the laboratory, to confine the growth of bacteria to surface patterns of desired, 2-D shapes. They were able to control the growth of the biofilm with the surface material, allowing the biofilm to form in some places and restricting its growth in others. Additionally, they found that when confined in two dimensions, the biofilm grew in a 3-D — that is, building vertically.

The SU researchers found that they key principle was in preventing protein from sticking to a surface. Do this, they decided, and you could also prevent both bacteria and mammalian cells from doing likewise.

Luk said that the goal was to prevent, specifically, three things: "protein absorption, mammalian cell adhesion," and the cell/surface adhesion.

To do this, their hypothesis was that an "organization of water structure" at the interface between surface and cell protein materials could be formed to resist what he termed "the befouling" caused by these adhesive activities.

"Experimentally, we confirmed that this hypothesis also applies for mammalian cell adhesion and biofilm formation."

The researchers say that, in the process of demonstrating this new surface architecture, they also have developed a technology that scientists can use to study biofilms in ways that were not previously possible.

On the surface material they created, they were able to manipulate and confine biofilm growth four times longer than current technologies.

In other experiments, the scientists discovered important differences in the way mammalian cells attach to a surface and how a bacteria does this. "Our surfaces are able to reveal that mammalian cell adhesion requires the existence of an anchor, while bacteria can adhere to almost any sticky surface," Luk said.

Luk and Ren say that their discoveries and the surface technology they developed can be used to answer critical questions that previously eluded scientists and may lead to the better prevention of biofouling on medical implants.

"This level of surface control has never before been achieved," Ren said. "We hope that what we have learned in the laboratory will help answer other fundamental questions in surface materials research . . ."

"If we can transfer this surface chemistry onto microdevices, we have the potential for improving artificial organs and medical implants – catheters, tubes and so on — that resist immune response," Luk told MDD. "We are intending to make this commercially possible."

And in an e-mail follow-up to the interview with MDD, he said that a patent on the discoveries has been filed by a lead researcher he previously worked with at the University of Chicago, and "another one is in process here at SU, focused on transferring the surface chemistry to specific material applications."

Their work — supported by grants from the National Science Foundation — was reported in the Feb. 4 online version of ChemComm, the journal of the Royal Society of Chemistry (London/Cambridge), the largest chemical sciences organization in Europe, and in online and printed versions of Langmuir, published by the American Chemical Society (Washington).

No Comments